High Iodine Adsorption Research Articles

Strong acid- and irradiation-resistant nitrogen-rich covalent organic polymers with high iodine adsorption capacity

The removal of radioactive iodine from nuclear waste is very important for the development of nuclear energy. Covalent organic polymers (COPs) have been widely investigated for iodine capture due to their simple operation, diverse structures, and abundant pores. However, the disposal of nuclear waste in a strongly acidic and radioactive environment is still a great challenge. Herein, three nitrogen-rich COPs were successfully designed and synthesized by Schiff-base polycondensation reactions. The high density of N atoms in triazines and imines enhanced the binding capacity of iodine molecules, with an optimal gas-phase iodine adsorption capacity of 4.98 g g−1 and a liquid-phase iodine adsorption capacity of 1224.6 mg g−1. The backbone structure of the hydrazone bond connection and the introduction of thiophene effectively enhanced the stability of the TZ-COPs. The adsorption performance of TZ-2 was maintained after 6 M HNO3 immersion and 100 kGy radiation irradiation, respectively. In addition, TZ-2 still has 92.32 % adsorption performance in five cycles, with excellent reversible regeneration ability. Therefore, this work is important for the preparation of nitrogen-rich COPs for the efficient and reversible removal of radioiodine from nuclear waste.

Preparation of novel fluorinated highly branched (A3 + B3)‐type hyperbranched poly(amide‐imides) for electrochromism and iodine adsorption

AbstractIn this study, a series of (A3 + B3)‐type fluorinated hyperbranched poly(amide‐imides) were successfully synthesized with carbazole and fluorene units as end‐capping moieties. All synthesized end‐capping hyperbranched PAIs showed over 70% branching as determined by 1H NMR, demonstrating good solubility and thermal stability (Tgs: 242–263°C, T10%: 576–629°C). The HOMO and LUMO energy levels of hyperbranched PAI films were measured at 4.65–4.73 and 1.51–1.66 eV, respectively, suggesting favorable reoxidation and reduction characteristics. PAI‐2 demonstrates a 46.6% transmittance variation (∆T, 418 nm), along with a coloring/bleaching process time of 2.3 s/1.6 s, a coloring efficiency (CE) of 310 cm2/C, and exceptional redox stability over 100 cycles. Furthermore, the synthesized PAIs containing electron‐withdrawing groups exhibited a high iodine adsorption capacity as determined by iodine adsorption tests (PAI‐1: 534 mg/g, PAI‐2: 579 mg/g, PAI‐3: 490 mg/g).

The N,N,N′,N′-tetraphenylbenzidine-based conjugated hypercrosslinked polymers for adsorping iodine and fluorescence sensing 2,4-dinitrophenol, iodine

Although progress has been made in the development of hypercrosslinked polymers (HCPs) for iodine uptake, their fluorescence performance and fluorescence sensing performance are rare due to the lack of conjugated behavior in common HCPs. Herein, the N,N,N′,N′-tetraphenylbenzidine-based conjugated hyper-crosslinked polymers (conjugated TPB-based HCPs) were efficiently fabricated via a one-step Friedel-Crafts arylation reaction by selecting N,N,N′,N′-tetraphenylbenzidine (TPB) and N,N′-diphenyl-N,N′-di(m-tolyl)benzidine (DPDB) as the basic building blocks and p-dimethoxybenzene (DMB) as an external crosslinker which will lead to the formation of the conjugated structures. The derived TPB-based HCPs (denoted as, TPB-DMB and DPDB-DMB) possessed excellent stability and high surface areas, Their iodine adsorption capacities are up to 4.25 and 3.56 g·g−1. The high iodine adsorption is caused by chemical adsorption. The fully conjugated structure and the 3D aryl network give the conjugated TPB-based HCPs excellent luminescence properties and fluorescence sensing properties for 2,4-dinitrophenol and iodine. The fluorescence sensing mechanisms of the conjugated TPB-based HCPs for DNP and I2 includes photo-induced electron process and the resonance energy transfer process. This study provides a viable approach for the development of highly efficient iodine sorbents and fluorescence sensors of DNP and iodine for addressing environmental issues.

Porous Aromatic Frameworks Enabling Polyiodide Confinement toward High Capacity and Long Lifespan Zinc-Iodine Batteries.

Aqueous zinc-iodine batteries (AZIBs) are attracting increasing attention because of their high safety and abundance of resources. However, the performance of AZIBs is compromised by inadequate confinement of soluble polyiodides, the undesired shuttle effect, and slow reaction kinetics. In this study, a porous aromatic framework (PAF) with abundant benzene motifs and a well-organized pore structure is adopted as the iodine host, which exhibits high iodine adsorption capacity and robust polyiodide confinement. Both experimental characterizations and theoretical simulations indicate that the interactions between iodine species and the PAF-1 facilitate the redox reaction by coupling the electronic structures of the active species in the framework. A comparison of PAF-1, PAF-5, and PAF-11 also emphasizes the structural advantages of the high surface area and interconnected three-dimensional channels of PAF-1. Consequently, the I2@PAF-1 cathode can deliver a high capacity of 328 mAh g-1 at 0.5 C, outstanding rate performance, and a stable cycling life of 20000 cycles (86 % retention at 10 C). The robust polyiodide confinement and superb electrochemical performance of Zn-I2@PAF-1 provide insights into the practical application of PAFs as excellent electrode materials for AZIBs.

Design of Silk Fabric Surface with Enhanced Antiseptic Properties through Graft Modification and Iodophor Integration

AbstractTo improve the hydrophobic character of silk and impart iodine complex ion adsorption, the surface of woven silk fabric is enriched by different functional groups through the grafting of N‐vinylpyrrolidone (NVP), ethylene glycol dimethacrylate (EGDMA), and their mixtures (NVP–EGDMA). The dominant fibrous texture of silk enables an efficient graft copolymerization in terms of high grafting yield (>30%) after applying a mild degumming process. The structural and morphological alterations in the silk surface are evidenced with attenuated total reflectance‐fourier transform infrared spectroscopy (ATR‐FTIR), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) techniques. The imparted hydrophilicity property of the samples is revealed by contact angle–wetting time measurements. The usability of the graft‐modified samples as an iodophor polymeric substrate is then examined by treatment with I2/KI solutions, and the results are monitored using UV–vis spectroscopy. It is obtained that the NVP–EGDMA mixture‐grafted sample exhibits satisfactorily high iodine adsorption compared to untreated and NVP‐grafted silk samples, such as 0.05 g per 1 g fabric with high antibacterial activity against various pathogens, including methicillin‐resistant Staphylococcus aureus (MRSA) responsible for hospital‐acquired infections. This finding evidences its potential as an alternative antiseptic tissue for biomedical applications.

The flexible DADM-based covalent organic frameworks constructed by flexible knots and 4,4′-diaminodiphenylmethane as a linker for fluorescence sensing nitrophenol and adsorping iodine

Enrichment of nitro-aromatic compounds (NACs) and radioactive iodine seriously threatens the health of humans, therefore, trace detection of NACs and the efficient capture and storage of radioactive iodine have attracted a great deal of attention in recent years. Herein, we present two highly efficient flexible DADM-based covalent organic frameworks (DADM-based COFs) for the fluorescence sensing of o-nitrophenol (o-NP) and p-nitrophenol (p-NP) and reversible iodine capture, namely TDADM and HDADM. The resulting TDADM and HDADM have excellent thermal and chemical stability, some crystallinity and high BET surface areas of 1035 and 958 m2 g−1, respectively. For fluorescence sensing, TDADM and HDADM show high sensitivity to o-NP and p-NP with quenching constants (Ksv) of 6.77 × 103 and 3.39 × 104 L mol−1, respectively. The fluorescence quenching of TDADM is caused by the action of photo-induced electron transfer (PET) processes. The fluorescence quenching of HDADM is caused by the co-action of PET and resonance energy transfer (RET) processes. For iodine capture, TDADM and HDADM exhibit high iodine capture capacities, which are severally up to 4.08 and 5.32 g g−1. Such high iodine adsorption amounts are caused by the electron transfer of the electron-rich flexible DADM-based COFs to the electron-deficient I2 into the polyiodide anion complexes.

Modified polyethyleneimine with abundant N/O/S-heteroatoms and aromatic segments: Convenient synthesis via sulfur-isocyanide-amine multicomponent reaction and application in high-performance iodine capture

With the continuous development of nuclear industry, the discharge of radioactive iodine (129I and 131I) become a potential danger to ecological environment. The development of high-performance iodine capture materials has important practical significance to reduce the harm of radioactive iodine. With the aim to construct new iodine-adsorbing polymer under the “bottom-up” structural designing guidance, using sulfur (S), branched polyethyleneimine (PEI) and 4,4’-oxybis(isocyanobenzene) (OBI) as starting substrates, a thiourea-modified PEI derivative (PEI-SIA) with abundant N/S/O-heteroatoms and aromatic molecular fragments was successfully prepared here via efficient sulfur-isocyanide-amine multicomponent polymerization (SIA-MCP). Characterization of PEI-SIA’s fundamental properties indicated that it is a new type of covalent organic polymer (COP). The iodine adsorption performance of PEI-SIA was systematically investigated. Experimental results showed that PEI-SIA can effectively adsorb iodine in steam (75 °C), cyclohexane, and aqueous phases, with the equilibrium adsorption capacities up to 6.48, 2.63, and 3.01 g g−1, respectively. The iodine adsorption mechanism of PEI-SIA was characterized by experimental investigation and Density Functional Theory (DFT) calculation. The results revealed that PEI-SIA’s high iodine adsorption performance can be attributed to the synergistic effect brought by N/S/O-containing segments and the electron rich aromatic skeletons in PEI-SIA.

Recent progress in iodine capture by macrocycles and cages.

The effective capture of radioiodine is vital to the development of the nuclear industry and ecological environmental protection. There is, therefore, a continuously growing research exploration in various types of solid-state materials for iodine capture. During the last decade, the potential of using macrocycle and cage-based supramolecular materials in effective uptake and separation of radioactive iodine has been demonstrated. Interest in the application of these materials in iodine capture originates from their diversified porous characteristics, abundant host-guest chemistry, high iodine affinity and adsorption capacity, high stability in various environments, facile modification and functionalization, and intrinsic structural flexibility, among other attributes. Herein, recent progress in macrocycle and cage-based solid-state materials, including pure discrete macrocycles and cages, and their polymeric forms, for iodine capture is summarized and discussed with an emphasis on iodine capture capacities, mechanisms, and design strategies.

Accurate construction of monolayer, bilayer, sandwich bilayer, four-layer, multi-layer and chiral bilayer 2D pillararene-type supramolecular networks.

The accurate construction of mono-, bi- and multi-layer networks has been an important challenge, especially for bi- and multi-layer networks. Monolayer, bilayer, sandwich bilayer, four-layer, and multi-layer two-dimensional pillararene-type metal-organic coordination networks have been constructed from functionalized pillar[5]arene and pillar[6]arene by utilizing the coordination interaction of cobalt and copper ions and combining with temperature control and guest induction. These two-dimensional coordination networks exhibit the excellent plasticity of pillararenes and structural variety, which are characterized by X-ray single crystal diffraction and PXRD, confirming that pillararenes units can function as excellent tunable scaffolds for structural regulation. Two-dimensional chiral double-layer structure products are also constructed from R- and S-pillar[6]arene, which are obtained by high-performance liquid chromatography. Atomic force microscopic imaging confirms the thicknesses of these networks. Moreover, these networks also exhibit high iodine adsorption capacity in aqueous environments at ambient temperature. The monolayer, bilayer, sandwich bilayer, four-layer and multi-layer structures of the pillararene-type networks represent a new facile supramolecular self-assembly strategy and platform for designing more mono-, bi- and multi-layer two-dimensional nanomaterials and chiral two-dimensional double-layer structures provide a new method for the construction of more two-dimensional chiral polymers.

Covalent organic polyrotaxanes based on β-cyclodextrin for iodine capture.

Herein, covalent organic polyrotaxanes (COPRs) were integrated with supermolecule self-assembly and dynamic imine bond formation to act as absorbents that captured radioactive iodine from water. The aromatic building blocks were initially complexed with β-cyclodextrin (β-CD) to form pseudorotaxanes, which were then condensed with aromatic tri-aldehyde via mechanical grinding and solvothermal synthesis in sequence. The threading of β-CD throughout the polymer skeleton effectively reduced the usage of expensive building blocks and significantly lowered the cost, while also remarkably enhancing the skeleton polarity, which is closely related to many special applications. Impressively, the threading of CD improved the water dispersibility of COPRs, which displayed an abnormally high iodine adsorption capacity. This novel synthetic strategy allows the incorporation of mechanically interlocked CDs into porous polymeric materials, which provides access to low-cost preparations of COPRs with a brand new structure for specific applications.

Fabrication of bimetallic MOF-74 derived materials for high-efficiency adsorption of iodine.

Owing to their high porosity, open metal sites, and huge surface area, metal-organic framework (MOF) materials are commonly employed in iodine adsorption processes. Bimetallic MOFs have drawn a lot of attention since mono-metal MOFs have been unable to keep up with the demand. Bimetallic MOF materials still have drawbacks, including limited adsorption capacity, extended adsorption time, poor stability, and poor selectivity, despite their positive performance in radioactive iodine capture. It has been therefore difficult to develop adsorbents with quick iodine adsorption rates and high iodine adsorption efficiency. This study investigated the adsorption properties of a series of bimetallic MOF-74 materials (Mn-Co-MOF-74, Mn-Zn-MOF-74, and Mn-Ni-MOF-74) for radioactive iodine, as well as their design and synthesis utilizing the reflux approach. It was discovered that the adsorption performance of Mn-Ni-MOF-74 for radioiodine was superior to that of the other two bimetallic MOF-74 materials. Using the bimetallic Mn-Ni-MOF-74 as a precursor, a variety of bimetallic MOF-74 derived carbon compounds (Mn-Ni-CX) were prepared by high-temperature pyrolysis. Simultaneously, the structure of the material and the iodine adsorption characteristics have been thoroughly studied.

Efficient capture of iodine by charge-induced effect of nitrogen-rich ionic liquids

The efficient capture of radioactive iodine in nuclear waste is vital for promoting the sustainable development of nuclear energy, protecting the environment and human health. Nitrogen-rich adsorbents have received widespread attention due to their high affinity with iodine. Herein, we present a series of nitrogen-rich heterocyclic ionic liquids based on 5-aminotetrazolate (ATILs), and fabricate four composite materials ([N1111][AT]/MF, [N2222][AT]/MF, [N3333][AT]/MF, [N4444][AT]/MF). MF with porous properties as a carrier is cost-effective and readily available. For the composite materials, the ATILs possess abundant nitrogen active sites, and the introduction of MF significantly increases their specific surface area. This greatly enhances the iodine capture performance of materials. The maximum capture capacities of [N1111][AT]/MF, [N2222][AT]/MF, [N3333][AT]/MF and [N4444][AT]/MF were 6.94 g g−1, 6.53 g g−1, 5.70 g g−1 and 4.58 g g−1, respectively. A certain correlation between capture performance and nitrogen content can be found. Increasing the nitrogen content of material can still contribute to enhancing its performance, even when the nitrogen content exceeds 35 %. FT-IR, Raman and XPS spectra confirmed that the polyiodide anions were produced via charge-inductive effect and charge transfer. The density functional theory (DFT) calculation confirmed the feasibility of nitrogen-rich strategies and the existence of strong halogen bonds between I2 and 5-aminotetrazolate anions. This work obtained a series of iodine capture materials with high nitrogen content, achieved efficient iodine capture, and demonstrated the relationship between materials with high nitrogen content and iodine adsorption performance, which will promote the design and development of novel nitrogen-rich materials for iodine capture.

Influence of potential contaminants on I2 and CH3I adsorption onto zeolitic imidazolate frameworks (ZIFs) using GCMC simulations

Zeolitic imidazolate frameworks (ZIFs) are one type of promising volatile radioiodine sorbents due to their chemical/thermal stability, tunable structures, and high iodine adsorption capacity. However, the inhibiting effect of contaminants on volatile iodine adsorption onto ZIFs remains unclear. Herein, the adsorption of volatile iodine (I2 and CH3I) onto five different ZIFs (SALEM-2, ZIF-8, ZIF-Cl, ZIF-90, and ZIF-65) and adsorption selectivity over ten contaminants were investigated by using grand canonical Monte Carlo (GCMC) methods. It is found that the I2 adsorption isotherm could be accurately described by the Langmuir-Freundlich model. Furthermore, the adsorption quantity of CH3I is much smaller than that of I2 at the same partial pressure. Ten potential gaseous contaminants that existed in a reprocessing plant or nuclear reactor accident, including CO, NO, H2O, CH4, C2H6, CH3OH, CH3CH2OH, Cl2, CH3Cl, and C6H6, were considered for calculation of binary adsorption. The results show that C6H6 has the largest adsorption enthalpy among all contaminants, whereas CO, NO, H2O, and CH4 have the smallest. Moreover, CO, NO, H2O, and CH4 have negligible effects on volatile iodine adsorption onto ZIFs. In contrast, except for CH3I adsorption onto ZIF-65, C6H6 has the strongest inhibiting effect since benzene could occupy the adsorption sites of iodine in ZIFs. This work not only provided the fundamental knowledge of volatile iodine adsorption on ZIFs but also proposed a new strategy to evaluate the inhibiting effect of contaminants. It could be helpful for future screening and design of better sorbents.

Simultaneous optimization of carbon yield and iodine adsorption of ACFs derived from carpet wastes

AbstractRecycling post‐consumer carpet waste is a critical consideration for decreasing the environmental hazard of non‐biodegradable plastics. Therefore, the manufacturing of activated carbon fibres (ACFs) from post‐consumer carpet waste treated with KOH was modelled and optimized by the response surface methodology (RSM). The simultaneous effects of carbonization rate, pyrolysis temperature, and activation time on the performance of carpet waste‐based ACFs were studied. Box–Behnken design (BBD) was applied to study the influence of three significant processing parameters on the carbon yield and iodine adsorption of synthesized ACFs. The RSM analysis established that pyrolysis temperature was the most important parameter affecting the ACFs' performance. The optimum settings that led to the production of high carbon yield and iodine adsorption of ACFs were a carbonization rate of 5.4°C/min, pyrolysis temperature of 705.7°C, and activation time of 83 min. The carbon yield and iodine adsorption under the above conditions were obtained at 49.8 ± 0.9 wt.% and 1351 ± 45 mg/g, respectively. BBD has been established to be a powerful approach in modelling and optimization to achieve high‐quality of iodine adsorbents from carpet wastes.

Rational Design and Assembly of Two-Dimensional Layered Metal–Organic Frameworks: Structure, Morphology, Fluorescence Regulation, and High Iodine Adsorption

Two-dimensional (2D) layered metal–organic frameworks (LMOFs), an emerging type of 2D materials, have aroused significant attention recently. Although a great number of LMOFs with diverse topologies have been reported, their predictable preparation remains challenging. Inspired by the transformation of three-dimensional pillared-layer MOFs (PLMOFs) to 2D layers via solvent-assisted link exchanging, we developed herein a novel de novo synthesis strategy, i.e., in situ capping, for the rational fabrication of 2D LMOFs. During PLMOF construction, the pillars are in situ substituted by terminal ligands to seal both sides of the instantaneously generated layers, forming the targeted 2D LMOFs. Employing such a strategy, 2D LMOFs {[Zn(hsb-2)(benzoate)2]·0.5H2O}n (HSB-W11), [Zn(hsb-2)(2-benzoylbenzoate)2]n (HSB-W12), [Zn(hsb-2)(2-acetylbenzoate)2]n (HSB-W13), and {[Zn(hsb-2)(2-naphthoate)2]·DMF·H2O}n (HSB-W14) were obtained predictably by exchanging the terephthalate pillar (bdc) of HSB-W1 (a 3D PLMOF composed of bdc and 1,2-bis(4′-pyridylmethylamino)-ethane) with the capping ligand benzoate or its analogues. The strategy is also valid for other PLMOF systems with bipyridine-type ligands as pillars, X-pcu-1-Zn, for example. Furthermore, the undersized materials of HSB-W11–W14 have been prepared by the instant in situ exfoliation method. The structure, morphology, and fluorescence were tuned by changing the anchoring terminal ligands. In addition, LMOFs HSB-W11–W14 were utilized as I2 adsorbents; remarkably, HSB-W13 displayed a record-high volatile iodine uptake at room temperature. The in situ capping strategy has many merits including high designability and efficiency, facile green synthesis, and atom economy, which may be widely adapted to fabricate diverse 2D LMOFs.

Facile Microwave-Assisted Synthesis of 2D Imine-Linked Covalent Organic Frameworks for Exceptional Iodine Capture.

Covalent organic frameworks (COFs) have emerged as auspicious porous adsorbents for radioiodine capture. However, their conventional solvothermal synthesis demands multiday synthetic times and anaerobic conditions, largely hampering their practical use. To tackle these challenges, we present a facile microwave-assisted synthesis of 2D imine-linked COFs, Mw-TFB-BD-X, (X = -CH3 and -OCH3) under air within just 1 h. The resultant COFs possessed higher crystallinity, better yields, and more uniform morphology than their solvothermal counterparts. Remarkably, Mw-TFB-BD-CH3 and Mw-TFB-BD-OCH3 exhibited exceptional iodine adsorption capacities of 7.83 g g-1 and 7.05 g g-1, respectively, placing them among the best-performing COF adsorbents for static iodine vapor capture. Moreover, Mw-TFB-BD-CH3 and Mw-TFB-BD-OCH3 can be reused 5 times with no apparent loss in the adsorption capacity. The exceptionally high iodine adsorption capacities and excellent reusability of COFs were mainly attributed to their uniform spherical morphology and enhanced chemical stability due to the in-built electron-donating groups, despite their low surface areas. This work establishes a benchmark for developing advanced iodine adsorbents that combine fast kinetics, high capacity, excellent reusability, and facile rapid synthesis, a set of appealing features that remain challenging to merge in COF adsorbents so far.

The constructions of the fully flexible s-triazine-based covalent organic frameworks for adsorping iodine and fluorescence sensing p-nitrophenol and iodine

The effective capture of radioactive vapor waste during fission is of great significance to the safe utilization of nuclear energy. Covalent organic frameworks (COFs) are a kind of novel porous crystal polymers, with highly flexible channel structure and molecular designability. COFs containing nitrogen-rich structures and flexible units can provide effective binding sites for adsorption of iodine, and are potential adsorption materials. In this study, the fully flexible s-triazine-based COFs were prepared by one-pot condensation using fully flexible building blocks of 2,4,6-tris(4-formylphenoxy)- 1,3,5-triazine (TPT–3–CHO) as a knot and ether-based diamines as flexible linkers. The three fully flexible s-triazine-based COFs have large surface areas (1490, 1596, and 1657 m2 g−1), good crystallinity and outstanding adsorption capacitiy of volatile iodine (4.10, 4.13 and 3.40 g g−1) with excellent recyclability. As the linker lengths increase, the specific surface areas increase, but the adsorption amounts of iodine decrease. Moreover, the fully flexible s-triazine-based COFs also have high sensitivities for fluorescence detection against p-nitrophenol and iodine. Their quenching constants (KSV) for p-nitrophenol are 5.59 × 104, 4.05 × 104 and 2.35 × 104 L mol−1, respectively. The fully flexible s-triazine-based COFs have larger specific surface area, high iodine adsorption, and more sensitive fluorescence sensing performance than the COFs formed by the corresponding rigid linkers.

Ammonia Removal in Activated Carbons Prepared from Olive Oil Industry Waste

Activated carbons (ACs) from olive stone were prepared using CO2, steam, KOH, and H3PO4 as activating agents. The resultant activated carbons were characterized by proximate and ultimate analysis, N2 adsorption (Brunauer-Emmett-Teller (BET) method), iodine number, Boehm titration, temperature-programmed desorption (TPD), and Fourier transform infrared spectroscopy (FTIR). Ammonia (NH3) was used as a test molecule to be adsorbed. The BET surface areas of the ACs obtained ranged from 1000 to 1986 m2 g-1. Type I isotherms were obtained for all the samples, although steam and H3PO4 ACs showed a significant mesopore contribution. KOH activation resulted in carbon with a high microporosity (98%) and high iodine adsorption (1030 mg g-1). KOH AC prepared with a KOH/pyrolyzed char weight ratio of 2 and at 900 °C showed the highest NH3 adsorption (252 mg g-1), favored by the high microporosity and adequate acidity. Chemical activation (KOH and H3PO4) promotes higher NH3 adsorption than the physical ACs prepared (CO2 and steam). Langmuir and Freundlich adsorption equilibrium models were used to correlate the NH3 adsorption isotherms, obtaining the best fit for the Freundlich equation. The results indicated that olive stone-based activated carbon could be used for commercial AC to remove NH3 from gaseous streams.

Synthesis and structural characterization of new group 12 metal ions coordination polymers built on sulfur‐based ligand and probing their high iodine adsorption efficiency in micro and bulk forms

In this work, we have prepared two new sulfur CPs with group 12 transition metals, namely,[Zn (NCS)Cl(μ2‐L)]n(1)and[Hg (SCN)2(μ2‐L)]n(3).[Cd (NCS)Cl(μ2‐L)]n(2), which is isostructural with1, was synthesized for a comparison from our published work. These compounds have been characterized by FT‐IR, UV–Vis, powder X‐ray diffraction (PXRD), elemental analysis (CHNS), scanning electron microscopy (Fe‐SEM), TGA, BET, and single‐crystal X‐ray analysis for1and3. In the structure of all polymers, the bbit ligand [L = bbit = 1,1‐bis(3‐methyl‐4‐imidazoline‐2‐thion)butane] is bridged between metal centers by the anti‐anti‐anti conformation to form an infinite 1D zigzag chain. The considered polymers were used for the removal of a substantial amount of I2from cyclohexane solution. Despite the nonporous and low dimensional frameworks of title polymers, their maximum iodine adsorption capacities were notable and in order of 817.68, 906.48, and 911.08 mg/g for polymers1–3, respectively, with an extraordinary stability toward iodine. The capacity of micro‐sized structures was almost double as compared with their bulk ones.

A Zirconium-Organic Framework Constructed from Saddle-Shaped Tetratopic Carboxylate for High-Rate and -Efficiency Iodine Capture.

Metal-organic frameworks (MOFs) exhibit strong potential for applications in molecular adsorption and separation because of their highly tunable structures and large specific surface areas and have also been used for iodine capture. However, most works on MOF-based iodine capture focus on the adsorption capacity while taking little consideration of the capture rate and efficiency. Herein, we report the design of a saddle-shaped tetratopic carboxylic acid containing four thiophene groups (H4COTTBA) and the synthesis of a 4,8-connected flu-type zirconium MOF (HIAM-4014) using this linker. HIAM-4014 exhibits highly efficient iodine capture. The large cagelike pore structure, OH- groups on the unsaturated Zr6 clusters, electron-rich nature of the thiophene group in the linker, and high surface area are all attributed to the tetrahedral geometry of H4COTTBA, which endows HIAM-4014 with a relatively high iodine adsorption capacity of 2.50 g/g within 2 h and an equilibrium adsorption capacity of 2.68 g/g after 5 h. Coupled with a high elution ratio and great recyclability, HIAM-4014 is a good candidate for the efficient removal of waste iodine.